A Timesaving Approach to Sample Prep

(click for larger image) Table 1: Recovery and % CV of acrylamide.

Phenomenex—Novum SLE. With a synthetic SLE sorbent, scientists can expect consistent results from batch to batch due to the stringent manufacturing and QC processes behind the lab-engineered product. This consistency and reliability is important when analyzing low-level contaminants such as hazardous compounds in food.

To test the effectiveness of the new, synthetic SLE sorbent in a food safety testing setting, acrylamide was extracted from both ground coffee and instant coffee.

SLE Extraction Protocol

1. Coffee pretreatment: Ground coffee, 40 milligrams (mg)/milliliter (mL)
   • 60 grams of ground coffee was percolated with 1,500 mL of boiling water Instant coffee, 8 mg/mL
   • 2 grams of instant coffee was dissolved in 250 mL of boiling water Coffee was allowed to reach room temperature and was then spiked with acrylamide to reach 100 nanogram (ng)/mL (ground coffee) and 200 ng/mL (instant coffee) by adding 20 microliter (µL) acrylamide-13C3 (4 microgram/mL in water) to 800 µL of the prepared coffee. The 150 µL of 2 percent ammonium hydroxide in water was added to the spiked samples that were then vortexed for 30 seconds.
2. Load the pretreated sample onto a 6cc SLE tube.
3. Apply 5 inch Hg vacuum for 5 to 10 seconds to initiate flow into the sorbent.
4. Wait 5 minutes.
5. Load 2x 2.5 mL ethyl acetate/tetrahydrofuran (1:1) and collect under gravity in a collection tube that contains 10 µL ethylene glycol.
6. Apply 5 inch Hg vacuum for 20 to 30 seconds to complete elution.
7. Dry down and reconstitute in water.

After extraction there was an immediate visual difference between the initial sample (see Image 1) and the clean sample (see Image 2). The resulting clean sample was then analyzed by LC/MS/MS, which resulted in acrylamide recoveries of 94.9 percent from the ground coffee and 92.8 percent from the instant coffee, indicating that the SLE cleanup was not only effective at removing interferences but was also resulted in excellent analyte recoveries. In addition to high recoveries, the method produced % CV values of 0.78 (ground coffee) and 1.61 (instant coffee), which suggests that the extraction is also reproducible (see Table 1).

As the food safety industry continues to grow and monitor an increasing list of contaminants, testing laboratories must find effective and reliable ways to analyze a variety of food samples. Sample preparation is crucial when working with food samples because of the many complex components within the sample; however this is perhaps the most time-consuming step of the analytical process. The introduction of SLE to food safety testing is providing labs with a rapid yet clean solution to sample preparation that is not only consistent and reliable but can also be automated for further timesavings.

Pike is the strategic marketing manager of new products at Phenomenex. She received her Bachelors degree in biochemistry and molecular biology and her Masters degree in biotechnology from Boston University, Mass. Reach her at [email protected].